Dust blew over the Gulf of Alaska in early November 2011. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image on November 2, 2011.
Blowing toward the south-southwest, the dust plume remains discernible for roughly 100 kilometers (60 miles). The dust emerges from the Copper River Valley, which zigzags through the glacier-rich Chugach Mountains. The slow movement of glaciers over bedrock grinds the rock into glacial flour. This fine sediment is easily lofted into the air by winds blowing through mountain valleys.
This image also shows swirls of iridescent green in the waters along the shore. The bright green probably results from sediment and phytoplankton. Dust can fertilize phytoplankton, prompting big blooms, but the microscopic organisms also thrive in high-latitude seas especially near coastlines, without dust.
NASA image courtesy Jeff Schmaltz, MODIS Rapid Response Team at NASA GSFC. Caption by Michon Scott.